La _1.7 Sr _0.3 Co _0.5 Ni _0.5 O _4+δ layered perovskite as an efficient bifunctional electrocatalyst for rechargeable zinc-air batteries

In this work, a novel La _1.7 Sr _0.3 Co _0.5 Ni _0.5 O _4+δ with a layered perovskite structure was synthesized by the sol-gel method and characterized by the X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Catalytic activities of La _1.7 Sr _0.3 Co _0.5 Ni _0.5 O _4+δ toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were systematically investigated by the rotating disk electrode (RDE) technique in alkaline media. Compared to La ₂ NiO _4+δ , La _1.7 Sr _0.3 Co _0.5 Ni _0.5 O _4+δ demonstrated more active for ORR in terms of the higher limiting current density (−4.05 mA·cm ⁻² ) and higher half-wave potential (0.568 V vs. RHE) at 1600 rpm. Zinc-air batteries using La _1.7 Sr _0.3 Co _0.5 Ni _0.5 O _4+δ as the catalyst exhibited the higher peak power density (60 mW·cm ⁻² ), the lower discharge-charge voltage gap (1.26 V) after 100 cycles and good discharge-charge cycling stability than that of La ₂ NiO _4+δ .